首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   458篇
  免费   4篇
  国内免费   18篇
化学   321篇
晶体学   2篇
力学   8篇
数学   52篇
物理学   97篇
  2022年   11篇
  2021年   10篇
  2020年   23篇
  2019年   15篇
  2018年   18篇
  2017年   18篇
  2016年   19篇
  2015年   8篇
  2014年   19篇
  2013年   29篇
  2012年   13篇
  2011年   38篇
  2010年   45篇
  2009年   42篇
  2008年   24篇
  2007年   28篇
  2006年   13篇
  2005年   7篇
  2004年   5篇
  2003年   2篇
  2002年   8篇
  2001年   2篇
  1999年   1篇
  1998年   3篇
  1997年   3篇
  1996年   2篇
  1995年   5篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   6篇
  1984年   6篇
  1983年   4篇
  1982年   3篇
  1981年   3篇
  1980年   4篇
  1979年   5篇
  1978年   4篇
  1977年   5篇
  1976年   2篇
  1975年   4篇
  1974年   3篇
  1973年   4篇
  1972年   1篇
  1965年   1篇
排序方式: 共有480条查询结果,搜索用时 15 毫秒
1.
Russian Journal of Organic Chemistry - A new convenient method has been developed for the synthesis of quinazolinones from 2-phenyl-1H-indole and substituted amines under catalysis by...  相似文献   
2.
The concept of an extending ideal in a modular lattice is introduced. A translation of module-theoretical concept of ojectivity (i.e. generalized relative injectivity) in the context of the lattice of ideals of a modular lattice is introduced. In a modular lattice satisfying a certain condition, a characterization is given for direct summands of an extending ideal to be mutually ojective. We define exchangeable decomposition and internal exchange property of an ideal in a modular lattice. It is shown that a finite decomposition of an extending ideal is exchangeable if and only if its summands are mutually ojective.  相似文献   
3.
Calotropis procera (family: Asclepiadaceae) contains cardiac glycosides which are cytotoxic to cancer cells. The extracts of C. procera have been reported to be cytotoxic to many cancer cell lines and this is the first report against the human skin melanoma cells (SK-MEL-2). The SK-MEL-2 cells treated with C. procera methanolic extract (CPME) were analysed for growth inhibition and apoptosis. The exposure of phosphatidylserine in apoptotic SK-MEL-2 was analysed by using the Annexin-V FITC flow cytometry method. In CPME-treated SK-MEL-2 cells, 19.6% of apoptotic and 58.3% dead cells were observed. The 15.97% and 15.85% of early apoptotic cells were found at 20 μg/mL of the ouabain and paclitaxel, respectively. Active caspases, nuclear degradation confirmed apoptotic SK-MEL-2 cells in time- and dose-dependent manner. The cell cycle analysis shows that CPME treated cells halt at G2/M phase. Significant cytotoxic activity of CPME against SK-MEL-2 may be attributed to its high cardenolide content.  相似文献   
4.
A precise and accurate liquid chromatography–tandem mass spectrometric (LC–MS/MS) bioanalytical method has been developed and validated for the simultaneous quantification of WCK 4234 and meropenem (MEM) in dog plasma. Protein precipitation using acetonitrile was employed as a sample preparation approach. Cefepime was used as an internal standard. The developed method was selective, sensitive (limit of quantification, 0.075 μg/ml for both drugs), accurate (recovery > 90%), precise (CV < 10%) and linear (r2 ≥ 0.99, concentration range 0.075–120 μg/ml for both analytes). The developed method was successfully applied for the determination of both drugs in plasma to assess the pharmacokinetics in beagle dogs. WCK 4234 + MEM in a 1:1 ratio at 15 + 15 and 30 + 30 mg/kg doses were administered by the intravenous route. The mean plasma concentration and area under the concentration–time curve of WCK 4234 ranged from 38.3 to 77.4 μg/ml and from 47.8 to 77.1 μg h/ml, respectively, and the values for MEM ranged from 52.2 to 115.3 μg/ml and 70.5 to 133.6 μg h/ml respectively. The elimination half-life of WCK 4234 and MEM was around 0.8 h.  相似文献   
5.
JPC – Journal of Planar Chromatography – Modern TLC - A novel chromogenic reagent was developed for the identification and detection of organophosphorus herbicide. The organophosphorus...  相似文献   
6.
Antibiotic susceptibility test (AST) discs are used as an in-vitro diagnostic tool to select the appropriate antibiotic to treat an infection. Generally, the concentration of the drug loaded on to the AST discs is measured by studying its activity against quality control organisms. This methodology has several limitations—it is time consuming, requires trained manpower, has a wider acceptance criteria of zone of inhibitions—causing ambiguity in judging smaller variations in drug concentration. To overcome these issues, we have developed and validated high-performance liquid chromatographic (HPLC) methods for the determination of strength of AST discs for in-house researched antibiotics, namely Levonadifloxacin/WCK 771, Nafithromycin/WCK 4873, Cefepime-Tazobactam/WCK 4282, and Cefepime-Zidebactam/WCK 5222. The drugs were extracted from the AST discs using an appropriate solvent. The developed methods are simple, accurate, precise, reproducible, rugged, and robust. They are efficient in terms of time, and can be easily conducted in a quality control laboratory during release as well as stability evaluation of AST disc. Application of HPLC methods for the determination of strength of AST discs ensures flawless quality and, consequently, a better selection of drugs to treat bacterial infections in clinics.  相似文献   
7.
Research on Chemical Intermediates - A simple and efficient protocol has been developed for the synthesis of new1,2,3-triazole-2,3-dihydroquinazolin-4[1H]-one (DHQ) conjugates(6a?j) via...  相似文献   
8.
Cesium fluorides in ionic liquid [bmim][BF4] have been used to promote the Henry reaction effectively. These reactions proceed smoothly and afford an excellent yield of the products.  相似文献   
9.
10.
Russian Journal of Organic Chemistry - An efficient acid-catalyzed condensation between substituted benzohydrazides and 2,3,5,6-tetrafluoroterephthalic acid to form...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号